One-pot engineering TiO2/graphene interface for enhanced adsorption and photocatalytic degradation of multiple organics

It is challenging to design a multifunctional structure or composite for the simultaneous adsorption and photocatalytic degradation of organic pollutants in water. Towards this goal, in this work we innovatively engineered interfacial sites between TiO2 particles and reduced graphene oxide (RGO) sheets by employing an in situ one-pot one-step solvothermal method. The interface was associated with the content of RGO, solvothermal time and solvent ratio of n-pentanol to n-hexane. It was found that with a moderate amount of RGO (25%), TiO2 nanoparticles were well dispersed on the surface of the RGO or wrapped by the RGO, thus leading to full contact and strong interactions to form a Ti-O-C interfacial structure. But with low content of RGO (6%), TiO2 aggregates were a mixture of nanosheets, nanoparticles and nanorods. 25%RGO/TiO2 also had 175% higher surface area (146 m2 g-1), 95% larger volume (0.339 cm3 g-1) and smaller band gap than 6%RGO/TiO2. More importantly, 25%RGO/TiO2 demonstrated higher adsorption efficiency (25%) and four times faster degradation rate than TiO2 (0%). It also exhibited good capability to eliminate multiple organics and stable long-term cycle performance (up to 93% retention after 30 cycles). Its superiority was attributed to the large surface area and unique interface between the TiO2 and RGO, which not only provided more active sites to capture pollutants, but enhanced charge transfer (3 μA cm-2, five times higher than TiO2). This work offers a promising way to purify water through engineering new material structure and integrating adsorption and photodegradation technologies.